(a) Field of the Invention
The present invention relates to a liquid crystal display.
(b) Description of Related Art
Generally, a liquid crystal display (LCD) includes a liquid crystal (LC) panel unit including two panels provided with pixel electrodes and common electrodes, and an LC layer with dielectric anisotropy interposed therebetween. The pixel electrodes are arranged in a matrix and are connected to switching elements such as thin film transistors (TFT) to be sequentially applied with a data voltage for a row. The common electrodes cover the entire surface of the upper panel and are supplied with a common voltage. A pixel electrode, a common electrode, and the LC layer form an LC capacitor in a circuital view, and the LC capacitor together with a switching element connected thereto is a basic unit of a pixel.
The LCD is device which displays images by applying an electric field to a liquid crystal layer disposed between two panels and regulating the strength of the electric field to adjust a transmittance of light passing through the liquid crystal layer. Meanwhile, for preventing the LC layer from deteriorating due to a one-directional electric field, the polarity of the data voltage is reversed for each frame, for each row, or for each dot with respect to the common voltage, or the polarities of the data voltage and the common voltage are reversed together.
The LCD, as a small and medium sized display device, is used with a so-called dual display device that is being developed vigorously and which has panel units in each of its inner and outer sides.
The dual display device includes a main panel unit mounted on the inner side, a subsidiary panel unit mounted on the outer side, a driving flexible printed circuit film (FPC) provided with signal lines to transmit input signals from external devices, an auxiliary FPC connecting the main panel unit to the subsidiary panel unit, and an integration chip which controls the above-described elements.
The LCD includes a panel unit provided with pixels including switching elements and display signal lines, a gate driver providing a gate-on voltage and a gate-off voltage for gate lines of the display signal lines to turn on/off the switching elements, and a data driver providing a data signal for data lines of the display signal lines to apply a data voltage to the pixels via the turned-on switching elements, and the integration chip generates control signals and driving signals for controlling the main panel unit and the subsidiary panel unit, which is generally mounted as a COG (chip on glass) type. Additionally, the gate driver may be formed with the switching elements to be integrated on the edge of the panel unit.
Respective high voltage and low voltage lines are disposed at inner and outer sides along the edge of the panel unit in order to prevent electrostatic damage in the process of manufacturing the LCD. A diode unit including a plurality of diodes is connected between the high voltage line and the low voltage line, and the data lines are connected to the diode unit to release an electrostatic charge that penetrates into a center of the panel unit to the outside via a predetermined path, thereby protecting the panel unit.
The high and low voltage lines are connected between the integration chip and the gate driver, and transmit the gate-on voltage and the gate-off voltage, respectively, in a normal operation mode, e.g., for a mobile phone.
The integration chip applies a ground voltage of 0V to the low voltage line and 2.8V to 3.0V to the high voltage line in a stand-by mode in which it does not operate. In this way, when the stand-by mode is changed into the operation mode, a load of the high voltage line decreases to accelerate the operation of the integration chip upon application of the gate-on voltage having a relatively higher voltage to the high voltage line.
In this case, the diode functions as a resistor at its own turn-off to play a role in dividing a voltage between the high voltage line and the low voltage line. When leakage current flows in the data lines connected to the diode unit, the current is charged in the liquid crystal capacitor via the switching element to represent a pixel voltage. Thus, the liquid crystal is operated, thereby displaying stripes along the data lines in the stand-by mode of not displaying images.